STS-132: NASA refines processing targets for Atlantis’ Final Flight

October 5, 2009 by Chris Gebhardt

The first of what is scheduled to be the final three Launch Site Requirements Reviews (LSRRs) for the Space Shuttle Program (SSP) has been completed by managers at the Program Requirements Control Board (PRCB) for the STS-132 mission – the 32nd and final “scheduled” flight of orbiter Atlantis, due to launch in May 2010.

Flight Specifications:

In all, STS-132 will be the 132nd flight of the Shuttle Program and the 34th shuttle flight dedicated to construction and outfitting of the International Space Station. The 11+1+2 day flight of Atlantis will utilize External Tank 136, Reusable Solid Rocket Motor set 111, Solid Rocket Booster BI set 143, and operational software OI-34.

The primary payload for the mission remains the Russian Mini-Research Module 1 (MRM-1) and Integrated Cargo Carrier – Vertical Lightweight Deployable (ICC-VLD) pallet. The MRM-1 will be mounted toward the aft of the payload bay while the ICC-VLD will be berthed in the center for both launch and reentry.

The standard payloads of opportunity, MAUI, SEITI, SIMPLEX, and RAMBO 2 will be carried with Atlantis as well.

In the event of a contingency abort landing, all projected Orbiter weights are within specifications and limits.

Furthermore, should the mission end with a landing in California or New Mexico, the Shuttle Carrier Aircraft (SCA) NASA-911 is slated to be the SCA of choice for the ferry flight back to the Kennedy Space Center.

In all, the revised projections for Atlantis’ liftoff weight and Solid Rocket Booster/Space Shuttle Main Engine performance expectations (combined with the time of year the mission will be launched in) have yielded an Ascent Performance Margin of +2,058lbs.

This number is sure to change (i.e. decrease) in the coming months as NASA continues to evaluate ways to bring as much cargo to the International Space Station on the final Space Shuttle flights as possible.

Setting this LSRR apart from previous reviews is the lack of modifications NASA plans to make to orbiter Atlantis after the completion of her STS-129 mission in November 2009.

In fact, the LSRR document states that “No Orbiter Modifications have been identified to date for implementation” on Atlantis during the flow toward STS-132.

Likewise, the only documented work identified by the LSRR pertained to the closure of paperwork for a dash number configuration issue on the External Airlock and the continued use of the End Effector unit currently installed on Atlantis’ Shuttle Remote Manipulator System (SRMS) arm.

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Further information provided by the 64 page Launch Site Requirements Review presentation – available for download on L2 – pertained to the expected condition of Atlantis at the time of her final flight.

This conversation focused mainly on the Wing Leading Edge (WLE) Spar Inspections which come due in their entirety on January 22, 2010.

“Structural inspections of the wing leading edge spars are due prior to the last manifested flight of OV-104,” notes the LSRR presentation. “Performance of these inspections is intrusive and classified as a significant flow impact.”

In anticipation of this mandatory inspection, engineers involved with Atlantis – under the direction of OV-104 Flow Director Angie Brewer – have already completed spar inspections of 11 Left Hand (LH) WLE panels and 9 Right Hand (RH) WLE panels (also known as Reinforced Carbon-Carbon – or RCC – panels).

These inspections were accomplished during the second Orbiter Processing Facility (OPF) flow toward STS-125 and the flow toward the STS-129 mission.

Over the past year, Program managers had been discussing the possibility of foregoing a complete WLE spar inspection, with a final decision on whether or not to press ahead with a complete spar inspection on the recommendation of flight safety and the findings of the initial spar inspections.

While the spar inspections to date have yielded no concerns for flight and vehicle safety, it has been decided that a complete inspection of WLE spars on Atlantis will be completed prior to January 22, 2010.

The last complete WLE spar inspection on Atlantis was accomplished in July 2003, with a previous complete spar inspection in December 1997 during Atlantis’ Orbiter Modification Down Period (OMDP).

Prior to the Columbia accident, the next complete spar inspection was slated to take place after Flight 29 of Atlantis during her next scheduled OMDP.

However, with the realignment of the Shuttle Manifest after Columbia, and the initial desire to retire Atlantis after Flight 30 to eliminate a cost-inefficient OMDP, the need to perform this spar inspection was rendered moot.

Nevertheless, the reversal of Atlantis’ fate and the addition to two extra flights into 2010 for NASA’s now-middle Orbiter reintroduced the need to perform these inspections.

In all 12 RCC panels and associated spar fittings (panels 10-16 LH and 12-16 RH) were removed, examined, and reinstalled during Atlantis’ flow to STS-129 next month.

Potential Changes/Waivers:

In addition to the documented paper work closures and vehicle condition, the LSRR further notes a few potential changes for Atlantis.

The first such change would be to the Starboard Lightweight Tool Stowage Assembly. This Assembly has been identified for the potential addition of a cushion; however, analysis on whether or not this will be required is still ongoing.

Another potential change to Atlantis would be the re-torqueing of Windows #2 and #5.

Windows #2 and #5 on Atlantis have been re-torqued ahead of STS-129 to the 70 in-lbs requirement set by the Orbiter Project Office.

Whether or not these windows, or others on Atlantis, will have to be re-torqued prior to STS-132 is unknown at this time.

The final potential change – which would come in the form of a waiver – is an extension to the Auxiliary Power Unit (APU) Wetted Time requirement.

“APUs are due to be replaced prior to the last manifested flight of OV-104, STS-132, based on the 5 year wetted time requirement,” notes the LSRR presentation.

Currently, there are five spare APUs available for the entire Shuttle fleet through the end of planned operations in 2010.

In all, four APUs in the Shuttle fleet are affected by the five year wetted time requirement in 2010 – three of those being on Atlantis.

This leaves one spare APU for the fleet – an APU which, based on processing history, will be used via one “unplanned removal based on logistics projections.”

As such, the Shuttle Program has opened discussions on the possibility of waiving this requirement for Atlantis’ final flight, thereby preserving three APUs in stock.

Recently, the allowable APU wetted time was extended from four years to five years based on historical data.

Nevertheless, a significant amount of testing would be required to extend the wetted time requirement any further – even for just one flight.

As such, an APU wetted time extension was presented at the LOCCB on September 17 with approval to begin testing via “disassembly and inspection of the Fleet Leader APU at the Vendor.”

The testing is scheduled to be completed by mid-December. If the testing yields positive data, and the APU wetted time requirement is extended to six years, than none of Atlantis’ APUs will have to be removed and replaced during the STS-132 flow due to the wetted time requirement.

L2 members: Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.